Order filling or commissioning systems are generally known in the art. Such systems are typically used in environments where a wide variety of articles are stored in inventory, and orders are received requesting specific quantities of selected articles. It is desirable to fulfill the orders as efficiently as possible so that a greater number of orders may be shipped.
In the pick-to-lights system generally known in the art, a central conveyor is positioned between a pair of racks. Each rack has a number of shelves wherein each shelf contains a specific type of article or stock keeping unit (SKU). Light and number displays are located near the front of each shelf. A computer is provided for receiving order information and operating the light and number displays according to the orders received. A box for holding each order is placed on the conveyor. In operation, a sequence of lights is illuminated according to the order information received by the computer. For example, the computer illuminates the light associated with the shelf holding a first article of an order and indicates the desired quantity of that article on the number display. The stock worker walks to the illuminated shelf, picks up the desired quantity of the article, and places the article(s) in the box on the conveyor. Before depositing the article(s) in the box, the stock worker presses a quitting switch which delivers a pick complete signal to the computer. In response to the pick complete signal, the computer illuminates the light associated with the shelf holding the next article on the order list in the same process is repeated. In most pick-to-lights systems, the orders must be filled sequentially, and therefore the process will be delayed by slow stock workers or out-of-stock items.
A commissioning system that allows orders to be filled out of sequence is disclosed in U.S. Pat. No. 5,943,841. This system uses a central conveyor positioned next to a plurality of racks for holding articles. A plurality of intermediate containers are positioned above the conveyor belt for temporarily receiving articles from the racks. Each container has a hinged bottom, and includes a light and a quitting switch. Stock workers are assigned to sections of the racks for transporting articles from the racks to the containers. Each stock worker wears a terminal which displays the selected article and quantity to be picked. A computer is operably connected to the terminals and the containers for directing the stock workers to pick the articles. In operation, each stock worker consults the terminal to determine the selected article and quantity for a current picking operation. The computer also illuminates a light associated with the desired container into which the current pick will be deposited. As a result, each stock worker may fulfill portions of several orders by placing the articles in the indicated containers as directed by the computer. Once all of the portions of an order are deposited in various of the containers, the computer controls the containers so that they discharge their contents at substantially the same section of the advancing conveyor, thereby grouping together a complete order. A similar system is also disclosed in commonly assigned U.S. patent application Ser. No. 09/754,762 entitled “Method and Apparatus for Filling Stock Orders,” which is incorporated herein by reference. The intermediate containers disclosed in these documents are, however, overly expensive to build. In addition, it can be difficult for the stock worker to determine which container, of the plurality of containers provided, is intended to receive the articles from the current pick.